These ATtiny414-Controlled Keychain Trinkets Are Designed to Welcome Incoming Freshmen

Keychain trinkets are inexpensive and easy-to-build devices that can help incoming freshmen feel welcome within the department.

Cameron Coward
4 years agoDisplays

If your experience was anything like mine, then starting at a new school as a freshman was probably pretty terrifying. Sirawit7205 wanted a nice way to welcome new freshmen into their department and make them feel like they belong. To accomplish that, they decided to make some keychain trinkets that display personalized messages. The trinkets they came up with are controlled by a Microchip ATtiny414 microcontroller, and they put together a tutorial explaining how they designed and built them.

Each trinket is powered by a single CR2032 coin cell battery. The custom message is shown on a single seven-segment display, and long strings of text can be output one character at a time. The message itself is stored within the code on the Microchip ATtiny414 microcontroller, which has 4KB of space available for very long messages. A small switch is used to toggle power, and the only other components are a capacitor and a handful of resistors.

Surprisingly, Sirawit7205 did not design a custom PCB for these keychain trinkets. Instead, they used a standard breakout board designed for the SOP28 chip package that the ATtiny414 comes in. The resistors, capacitor, coin cell battery holder, and seven-segment display are all soldered onto that breakout board. The result is an inexpensive and easy-to-build device that can help incoming freshmen feel welcome within the department.

Cameron Coward
Writer for Hackster News. Proud husband and dog dad. Maker and serial hobbyist.
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